The range of non-specific changes is being assessed in experimental and control material. The specificity of the morphologic manifestations of acute ischemic neuronal changes is assessed by means of histologic and histochemical techniques. Current methods of fixation are being modified in order to find a procedure whereby the affected neurons may be adequately fixed. Likewise, the changes in different types of post- mortem autolysis are studied in order to clarify the nature of the neuronal changes in ischemic lesions.